In July 2002, the CDC reported 17 infant deaths associated with confirmed pertussis in 12 different states and showed that pertussis incidence has recently tripled in infants too young to have received the standard three doses of pertussis-containing vaccine at 2, 4, and 6 months of age. Additional reports of increasing rates of infant pertussis in Canada and Europe also have appeared. Given these observations, we question if an additional dose of acellular pertussis vaccine (DTaP) administered at birth to infants born in areas with high rates of pertussis disease could be beneficial. Although a recent report of the administration of acellular pertussis vaccine to newborns demonstrated that the vaccine was safe and generated an immune response in these young infants, DTaP vaccine has not been administered to neonates. The central hypothesis is that an additional dose of DTaP at birth will be safe and provide an adequate immune response when compared to infants given the standard DTaP vaccination schedule. Therefore the specific aims are to determine the safety, the humoral immune response, and the cell-mediated response of an additional dose of DTaP given at birth. This is a prospective, randomized, controlled pilot study of the acellular pertussis vaccine combined with DTaP administered at birth. There will be 25 healthy infants in each group enrolled between 2- 14 days of life, with the investigational group receiving an extra dose of DTaP at birth. Both groups will receive the standard vaccinations recommended by the American Academy of Pediatrics. Venous blood will be obtained at birth, 6, 7, 17, and 18 months for the measurement of IgG to common pertussis antigens (pertussis toxin, pertactin, fimbrae, and filamentous hemagglutinin) and the cell-mediated responses. Because the increasing rates of neonatal pertussis disease and the possibility that a birth dose of DTaP could generate an earlier immune response and prevent disease within the first few months of life, we are proposing this pilot trial.